Pyridine → 3alpha-Acetoxy-20-ethoxy-21-formyl-5alpha-pregn-20-en-11-one

HRID 1973739Notes

Reaction equation

HRID 1973739 reaction equation
[C:1]([O:4][C@@H:5]1[CH2:24][CH2:23][C@@:22]2([CH3:25])[C@@H:7]([CH2:8][CH2:9][C@@H:10]3[C@@H:21]2[C:20](=[O:26])[CH2:19][C@@:18]2([CH3:27])[C@H:11]3[CH2:12][CH2:13][C@@H:14]2[C:15](=[O:17])[CH3:16])[CH2:6]1)(=[O:3])[CH3:2].N1[CH:33]=[CH:32]C=CC=1.[CH:34]([O-])([O-])[O:35]CC>Cl(O)(=O)(=O)=O>[C:1]([O:4][C@@H:5]1[CH2:24][CH2:23][C@@:22]2([CH3:25])[C@@H:7]([CH2:8][CH2:9][C@@H:10]3[C@@H:21]2[C:20](=[O:26])[CH2:19][C@@:18]2([CH3:27])[C@H:11]3[CH2:12][CH2:13][C@@H:14]2[C:15]([O:17][CH2:32][CH3:33])=[CH:16][CH:34]=[O:35])[CH2:6]1)(=[O:3])[CH3:2]

Participants

5

Reactant 3

HCID 1049PyridineHCID 118727973alpha-Acetoxy-5alpha-pregnane-11,20-dioneHCID 53630039Ethylorthoformate

Product 1

HCID 867342913alpha-Acetoxy-20-ethoxy-21-formyl-5alpha-pregn-20-en-11-one

Reagents, catalysts & solvents 1

HCID 24247Perchloric AcidCatalyst

Procedure

A stirred solution of 3α-acetoxy-5α-pregnane-11,20-dione (0.375 g.) in ethyl orthoformate (10 ml) at 0° was treated with 9 drops of 75% perchloric acid over 20 minutes. Ca 10 drops of pyridine were then added and the mixture was extracted with ice-cold ether. The organic layer was washed with N hydrochloric acid solution, then aqueous sodium hydrogen carbonate and finally water. It was dried (MgSO4) and evaporated. The residue (0.5 g) was purified by preparative t.l.c. (ethyl acetate/petrol, 1:3) and then crystallisation from methyl acetate/petrol to give the title compound (0.2 g), m.p. 150°-154°, [α]D - 59.8°, λmax. 258.9 nm (ε 15,900).

Workup

  1. extractionthe mixture was extracted with ice-cold ether
  2. washThe organic layer was washed with N hydrochloric acid solution
  3. dry with materialIt was dried (MgSO4)
  4. customevaporated
  5. customThe residue (0.5 g) was purified by preparative t.l.c
  6. custom(ethyl acetate/petrol, 1:3) and then crystallisation from methyl acetate/petrol

Sources & evidence

ORD record
ord-6ac4b03550d9435aa66274712c5040af
Source dataset
uspto-grants-1976_12
Patent number
US03998829

Reaction notes

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